I received an email from a Nissan Representative this morning with this information on the sound that the Nissan Leaf will produce:

In developing the sound system, Nissan studied behavioral research of the visually impaired and worked with cognitive and acoustic psychologists. After looking at applied original technology developed to reduce vehicle noise and conducting tests in Japan and abroad, the Approaching Vehicle Sound for Pedestrians system was created.

The sine-wave sound system sweeps from 2.5kHz at the high end to a low of 600Hz, an easily audible range across age groups. Nissan worked to avoid a sound range that would add unnecessary noise to the environment (around 1,000Hz).

Depending on the speed and status (accelerating or decelerating) of Nissan LEAF, the sound system will make sweeping, high-low sounds. For instance, when Nissan LEAF is started, the sound will be louder, so a visually impaired person would be aware that a nearby car was beginning operations. And when a car is in reverse, the system will generate an intermittent sound. The sound system ceases operation when Nissan LEAF tops 30km/h and enters a sound range where regular road noise is high. It engages again as Nissan LEAF slows to under 25km/h.

The system is controlled through a computer and synthesizer in the dash panel, and the sound is delivered through a speaker in the engine compartment. A switch inside the vehicle can turn off sounds temporarily. The system automatically resets to "On" at the next ignition cycle.

I was actually looking forward to a car that makes less noise pollution and this sounds much too loud and annoying (though maybe its been amplified in the video for demonstration)

Ive read it can be turned off/on but its always on by default on startup. I might turn it off but switch it on if theres a inattentive pedestrian in the way (and honking isnt appropriate) to let him know Im there.

Speaking of honking a low level honking button in addition to the typical horn would be great

Although there are those who have always lived embedded in "noise", and cannot get to sleep in very quiet situations, ...the "quiet" aspect of e-vehicles (of all sizes) is something many will come to find compelling.

Here, even the road (mostly freeway so far) noise is being reduced (over 90%, I believe) in some areas, both with surface grinding and smoothing, and special low-noise surfacing materials.

Going from a "treated" section of freeway to an "old" section ... is startling. Yep, wakes the driver right up.

But, without the strong road noise and the "thump, thump, thump" of the lane markers, how will the blind drivers be able to stay on the road?

Yeah, that wouldn't be annoying at all would it? It will more than likely freak out a blind person as they won't have ANY clue what the he11 that noise represents. The back up one is especially dumb. Cars don't have backup beepers now (OK the Prius does but the people outside can only hear it if the windows are open) and shy the little boys with their fart can mufflers, you generally can't hear an ICE engine from behind a car.

I'm sure it would not be at all difficult to install a "shut off" switch in the speaker wires under the hood for under a buck. The engineering types will, I'm sure, provide a more elegant solution once the cars are delivered.